This application is based on and incorporates herein by reference Japanese Patent Application No. 2000-130803 filed Apr. 28, 2000.
The present invention relates to a method and apparatus for monitoring a microcomputer provided in an electronic control unit.
A microcomputer provided in an electronic control unit (ECU) for vehicles is generally monitored to detect whether the microcomputer is functioning normally or not, whether an input to the microcomputer is normal or not, or whether arithmetic operation in the microcomputer is carried out accurately or not.
The monitoring is conducted, for example, by executing the watch-dog (WD) monitoring to detect whether the arithmetic calculation period in a monitoring integrated circuit (IC) is in the correct period or not by inputting the arithmetic calculation period to the monitoring IC from the microcomputer. It may also be conducted by comparing the arithmetic calculation result of each microcomputer by using additional microcomputer of the same structure as the microcomputer to conduct the arithmetic calculation operation.
However, the WD monitoring results in that the monitoring capability is insufficient because contents of monitoring are limited. The mutual monitoring using a couple of microcomputers results in that a fault cannot be detected if there is an error in data inputted to a couple of microcomputers and that monitoring cost becomes high because a couple of microcomputers are used.
It is therefore an object of the present invention to provide a method of monitoring a microcomputer without requiring a couple of microcomputers.
According to the present invention, a microcomputer and a peripheral IC are connected to communicate data with each other. The peripheral IC monitors a fault of the microcomputer based on the data received from the microcomputer. The monitoring operation may be executed by measuring an interval of calculation, calculation result and sequence of data transmitted from the microcomputer. The microcomputer monitors a fault of the peripheral IC based on the data received from the peripheral IC.